CA1162407A - Reinforcing and confining earth formations - Google Patents
Reinforcing and confining earth formationsInfo
- Publication number
- CA1162407A CA1162407A CA000365214A CA365214A CA1162407A CA 1162407 A CA1162407 A CA 1162407A CA 000365214 A CA000365214 A CA 000365214A CA 365214 A CA365214 A CA 365214A CA 1162407 A CA1162407 A CA 1162407A
- Authority
- CA
- Canada
- Prior art keywords
- limbs
- holes
- units
- retaining
- earth formation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/14—Lining predominantly with metal
- E21D11/15—Plate linings; Laggings, i.e. linings designed for holding back formation material or for transmitting the load to main supporting members
- E21D11/152—Laggings made of grids or nettings
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D20/00—Setting anchoring-bolts
- E21D20/02—Setting anchoring-bolts with provisions for grouting
Abstract
ABSTRACT
Reinforcing and confining an earth formation is effected by restraining units having retaining limbs for insertion into prepared holes in the formation and transverse portions for lying against the formation. The retaining limbs are inserted into the prepared holes and the transverse portions of the units are thus arranged to define a mesh-like arrangement anchored at least partially by the retaining limbs. The end regions of the transverse portions are anchored to and linked together to hold the transverse portions against the earth formation. The units normally have at least two retaining limbs and these limbs are forced into the holes to a depth of between about 0,5 and 2 metres.
Formations maybe provided in the limbs to inhibit removal of the limbs.
Reinforcing and confining an earth formation is effected by restraining units having retaining limbs for insertion into prepared holes in the formation and transverse portions for lying against the formation. The retaining limbs are inserted into the prepared holes and the transverse portions of the units are thus arranged to define a mesh-like arrangement anchored at least partially by the retaining limbs. The end regions of the transverse portions are anchored to and linked together to hold the transverse portions against the earth formation. The units normally have at least two retaining limbs and these limbs are forced into the holes to a depth of between about 0,5 and 2 metres.
Formations maybe provided in the limbs to inhibit removal of the limbs.
Description
1 3 62~0~
THIS INVENTION relates to a method of reinforcing and confining an earth formation, to units or use in such a method, and to suitable reinforcing and confining systems.
Support systems may be classified into two distinct forms, namely active support and passive support systems.
Active support systems may be described as those systems which after installation immediately exert and maintain restraint agalnst rock failure. Such systems are typified~by traditlonal steel rockbolt systems. The support potential is directly 10 related to the efficient utilisation of the tensile strength of the steel members used. Passive support systems may be ~
described as those systems which become effective only after rock failure has occurred. The resultant rock closure is then resisted by the passive support. Passive support systems are typified by steel or timber props and packs. Their support potential i9 related to their compressive strength. However, due to the buckling mode of failure, the full compressive strength is seldom utilised.
. , ~ :
1 1 62~7 The Applicant has therefore aime~ to provide a system using a rockbolting technique which would incorporate active and passive support to provide initial stiffness followed by yieldability.
The present invention thus provides a method of re-inforcing and confining an earth formation by means of a plurality of restraining units, the units having retaining limbs for insertion into prepared holes in the formation and transverse portions for lying substantially against the formation, wherein 10 the retaining limbs are inserted into the prepared holes and the transverse portions of the units are arranged to define a O
mesh-like arrangement anchored at least partially by the retaining limbs.
In this method, the end regions of the transverse portions may be anchored to hold the transverse portions sub-stantially against the earth formation. For example, at least some of the units can have at least two retaining limbs and these limbs are then forced into the holes to anchor the units.
The retaining limbs may normally be forced into the holes to a 20 depth of between about 0,5 and 2 metres.
In order to improve the anchoring of the transverse portions, the method may include linking at least some of the units to other units. For example, the retaining limbs of at least some of the units can be linked by locating elements when the retaining limbs are inserted into the respective holes.
These elements may be integral with or separate from the units.
., , ' 1 fi2~
The anchorage in this case is provided by the shape of ~he units, the locating elements, and multiple anchorage in the holes. The units then cross the face of the formation in various directions and they are linked together and can be anchored deep into the formation~ The mesh arrangement will oppose the deformati~n of the rock face and will transmit point loads across a large surface area.
In practice, the prepared holes in the earth formation can be formed in an array with the spacings between the holes 10 being substantially equal to the lengths of the transverse portions of selected units, and a plurality of retaining limbs can be inserted into the majoriky of said holes. The spacings between the holes can be in the range of 0,5 to l metre. Owing to its nature, the mesh arrangement will lie close to the contour of the earth formation. By using a standard drilling pattern with a constant spacing, it is possible to alter the mesh openings to cater for a large range of formations. This is done by simply placing larger or smaller numbers of units in each hole and by interlinking the units in different holes.
20 The mesh density can be further altered by changing the spacing of the drilling grid.
The retaining limbs may include means, such as kinks, for inhibiting the removal of the limbs from the holes, and the inhibiting means are then forced into the holes, for example by hammer blows, when the retaining limbs are inserted into the holes. Alternatively, or additionally, the retaining limbs can be grouted lnto the holes.
1 1 6~07 The invention also provides a system reinforcing and confining an earth formation, the system comprising a plurality of restraining units each having at least one retaining limb inserted into a respective hole in the earth formation and at least one transverse portion lying substantially against the formation, at least a substantial number of the holes receiving limbs of more than one unit and the transverse portions defining a mesh-like arrangement anchored at least partly by the reinforcing limbs.
At least some of the units can cGmprise a U-shaped configuration providing a pair of spaced retaininy limbs and a --transverse portion connecting the limbs, the transverse portions lying adjacent to the earth formation.
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Means may be provided for inhibiting removal of the limbs from the holes, if needed. The inhiblting means may comprise locking formations provided by the retaining limbs of the units for anchoring the limbs in the holes, and additionally or optionally may comprise grouting material anchoring the retaining limbs in the holes. The concept of using each hole 20 for multiple anchorage provides unique system characteristics.
The system becomes extremely fle~lble since the number of limbs inserted into each hole can be varied according to requirements.
Consequently, the tensile and shear strengths can be easily varied and a greater surface area can be provided for the bonding of the grout.
In one embodiment, the lengths of the retaining limbs are between 0,5 and 2 metre, and the lengths of the transverse portions are in the range of 0,5 to l metre.
A restraining unit suitable for an earth reinforcing and confining system may have a U-shaped configuration providing a pair of spaced retaining limbs for insertion into suitable spaced holes in an earth formation and a transverse portion connecting the limbs, the limbs having lengths of between 0,5 and 2 metres and including means for inhibiting removal of the 10 limbs from suitably prepared holes, and -the space in between the limbs being in the range of 0,5 and l metre.
Embodiments of the invention will now be described, by way of example, with'reference to the accompanying drawings, in which Figure l shows a restraining unit for a reinforcing and confining system;
Figure 2 is a cross-section through an earth formation illustrating part of a rock reinforcing and confining systPm;
Figure 3 shows an arrangement of part of the system of 20 Figure 2 in the direction of arrow III in Figure 2;
Figure 4 shows three different system patterns;
Figure 5 is a cross-section through a rock formation showing part of another system;
Figure 6 is a schematic representation of part of reinforc-ing and confining system; and Figures 7 to lO show reinforcing and confining uni.ts.
1 1 B2~07 Referrirlg firstly to Figure 1, a restraining unit 10 for a rock reinforcing and confining system comprises an element 12 of round iron bar. This bar has been bent so that it has a generally U-shaped configuration providing a pair of spaced retaining limbs 14 which are united by a transverse central portion 16 of the unit~
The limbs 14 extend away from opposite ends of the central portion 16 and the central portion is substantially perpendicular to the directions in which the limbs extend. As 10 shown in Figure 1, each limb is bent to form substantially sinusoidal locking kinks 18 at portions closer to the central portion 16 than to the free ends of the limbs. The limbs also have relatively straight portions 20 extending away from the locking kinks.
The element 12 may suitably have a diameter o~, for example, 9 mm and the limbs may be about 1 metre long. The central portion 16 may also be about 1 metre long, or possibly slightly less than this. Naturally, the lengths of the limbs and of the central portion will be varied depending on the 20 selected drill hole density and required drill hole depth.
In practice, rock units suitable for use with drill hole depths of 1 metre, 1,5 metre and 2 metres and drill hole spacings of 1 metre, 0,75 metres and 0,5 metres would probably suit most requirements.
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~ 1 ~2~
The unit of Fiyure 1 may be used in the reinforcing and confining system of Figure 6, part of which is shown in detail in Figures 2 and 3, by drilling holes 22 into a rock formation 24 with the central axes of the holes being the same distance apart as the limbs 14 of the units 10 to be used. The diameters of the holes should be selected to allow for an appropriate number of limbs to be anchored in each hole. The depths of the holes may be selected to allow for the limbs to be anchored to substantially their full depth.
10 Once the holes have been drilled into the rock forma-ton, the limbs of the units are inserted into the holes and are O
pushed into the holes until the locking kinks 18 reach the mouths of the holes. The limbs are then driven into the holes with a suitable hammer ând the kinks will serve to anchor the limbs in place. The kinks are shown out of proportion to the hole diameter in the Figures. Where rapid installation and a minimum support life is required, the units may be driven into position without any grout, relying solely on the action of the locking kinks to retain them in position. However, the unlts 20 will normally be grouted into position by grouting material 25 to protect them from deterioration.
The limbs 14 of the various UllitS passing into each hole may be passed through a central hole 26 in a locating element in the form of a locking washer 28 before being inserted into thë hole. The locking washer adjacent to each hole may then ensure that any direct loading on a particular unit will be transmitted to the adjacent units.
: ~ 3 ~07 g Once the limbs 14 of the units have been properly located in the holes 22, the central portions 16 of the units will effectively form a mesh formation close to the contour of the face of the rock formation. By using a standard drilling pattern with a constant spacing, it is possible to alter the mesh openings to cater for a large range of rock formation sizes. This is done by simply locating larger or smaller numbers of units in each hole and by interlinking different holes. The mesh density can be further altered by changing the 10 spacing of the drill holes.
Figure 4 shows three basic patterns of units based on a square-grid system of drill holes 22. The drill holes are arranged in logitudinal rows 30 which are spaced one metre apart and transverse rows 32 which are also spaced one metre apart. In the zone 34, units are driven into the holes 22 with their central portions 16 extending only in the directions of the rows 30 and 32. A square mesh pattern is thus formed.
In the zone 36, the mesh pattern shown in the zone 34 is continued but a diagonal pattern of additional units is 20 superimposed on the square pattern to form a relatively dense mesh pattern.
Finally, in zone 38, the square mesh pattern is no longer continued but the diagonal mesh arrangement is retained, forming a diamond mesh pattern. This ls the form shown in Figure 6.
~ J 62~07 Figure 4 thus illustrates that it is possible for the units to cross the rock formation in different directions while being linked together at points which are anchored deep into the rock formation. The resulting mesh formation will oppose the deformation of the rock formation and will transmit point loads across a large area.
With reference to Figure 5, the U-shaped units may be arranged to provide two or more mesh layers 40. In this case, an increased number of locating elements, in this case also 10locking washers 28, is preferably used, the washer 28 closest to the hole surrounding the limbs of the units forming all of q the layers, a second locking washer surrounding the limbs of the units forming the outer two layers and the third locking washer surrounding only the limbs of the units of the outer mesh layer. The layers may have limbs of differing lengths anchored in a common drill hole grid or in an alternative drill hole` grid. This arrangement lS particularly suitable for inhibiting the damaging effects of violent rock bursts because each consecutive layer of mesh takes load at different time 20intervals, preventing the instantaneous release of strain energy at the rock face.
In the past, rock support systems have mainly been active support systems, such as traditional rock bolt systems, which immediately exert and maintain restraint against rock failure action after installation or passive support systemsi such as steel or timber props and packs which become effective only after rock failure has occurred. The system of the .
' 1 ~ e24.07 --ll--invention can form a comp~site reinforcing and confininy structure such as that shown in Figure 6 ~the rock formation being omitted), and thus provides a support lining for a rock formation and in situ rock reinforcement. The system has active and passive support ability, providing increased stiff-ness of the reinforced rock formation and yieldability if the rock ~ormation begins to move.
The system may be used with suitable linings for sealing rock faces and helping to maintain the integrity of 10 rock faces. While the system can be used in combination with wire mesh, shotcrete or gunnite (that is cementitious mater~al projected forcibly against the rock face), or sprayed plastics linings, the system can enhance the yieldability and strength - of all these linings aliowing them to absorb strain energy release while still supporting a rock formation, wire mesh and shotcrete being most suitable.
Although the uni.ts have been described in connection with supporting rock formations, it is possible that they could also be used elsewhere. For example, they could be used as 20 reinforcing members for concrete work, for supporting the perimeter of yieldable concrete packs or in steel rope lacing for improving stope hanging wall support.
The material and shape of the unit will be selected to suit the particular application. Possible alternative shapes are shown in Figures 7 to lO.
1 ~ ~2~.07 The unit of Figure 7 is a simple L-shaped unit formed of similar material to the unit of Figure 1 but having a loop at the free end of its transverse portion.
The limbs of other units can pass through this loop when they are driven into holes in a rock formation, thus anchoring the free end of the transverse portion.
The units of Figures 8 and 9 are bent to form one and two doubled-back transverse portions, respectively.
This arrangement thus provides U-shaped formations which 10 servè the same purpose as the loop of Figure 7. The uni.t of Figure 10 simply has a double U-shaped configuration and can be used in a similar manner to two uni.ts of Figure 1.
, ~"'., ~ .
:
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THIS INVENTION relates to a method of reinforcing and confining an earth formation, to units or use in such a method, and to suitable reinforcing and confining systems.
Support systems may be classified into two distinct forms, namely active support and passive support systems.
Active support systems may be described as those systems which after installation immediately exert and maintain restraint agalnst rock failure. Such systems are typified~by traditlonal steel rockbolt systems. The support potential is directly 10 related to the efficient utilisation of the tensile strength of the steel members used. Passive support systems may be ~
described as those systems which become effective only after rock failure has occurred. The resultant rock closure is then resisted by the passive support. Passive support systems are typified by steel or timber props and packs. Their support potential i9 related to their compressive strength. However, due to the buckling mode of failure, the full compressive strength is seldom utilised.
. , ~ :
1 1 62~7 The Applicant has therefore aime~ to provide a system using a rockbolting technique which would incorporate active and passive support to provide initial stiffness followed by yieldability.
The present invention thus provides a method of re-inforcing and confining an earth formation by means of a plurality of restraining units, the units having retaining limbs for insertion into prepared holes in the formation and transverse portions for lying substantially against the formation, wherein 10 the retaining limbs are inserted into the prepared holes and the transverse portions of the units are arranged to define a O
mesh-like arrangement anchored at least partially by the retaining limbs.
In this method, the end regions of the transverse portions may be anchored to hold the transverse portions sub-stantially against the earth formation. For example, at least some of the units can have at least two retaining limbs and these limbs are then forced into the holes to anchor the units.
The retaining limbs may normally be forced into the holes to a 20 depth of between about 0,5 and 2 metres.
In order to improve the anchoring of the transverse portions, the method may include linking at least some of the units to other units. For example, the retaining limbs of at least some of the units can be linked by locating elements when the retaining limbs are inserted into the respective holes.
These elements may be integral with or separate from the units.
., , ' 1 fi2~
The anchorage in this case is provided by the shape of ~he units, the locating elements, and multiple anchorage in the holes. The units then cross the face of the formation in various directions and they are linked together and can be anchored deep into the formation~ The mesh arrangement will oppose the deformati~n of the rock face and will transmit point loads across a large surface area.
In practice, the prepared holes in the earth formation can be formed in an array with the spacings between the holes 10 being substantially equal to the lengths of the transverse portions of selected units, and a plurality of retaining limbs can be inserted into the majoriky of said holes. The spacings between the holes can be in the range of 0,5 to l metre. Owing to its nature, the mesh arrangement will lie close to the contour of the earth formation. By using a standard drilling pattern with a constant spacing, it is possible to alter the mesh openings to cater for a large range of formations. This is done by simply placing larger or smaller numbers of units in each hole and by interlinking the units in different holes.
20 The mesh density can be further altered by changing the spacing of the drilling grid.
The retaining limbs may include means, such as kinks, for inhibiting the removal of the limbs from the holes, and the inhibiting means are then forced into the holes, for example by hammer blows, when the retaining limbs are inserted into the holes. Alternatively, or additionally, the retaining limbs can be grouted lnto the holes.
1 1 6~07 The invention also provides a system reinforcing and confining an earth formation, the system comprising a plurality of restraining units each having at least one retaining limb inserted into a respective hole in the earth formation and at least one transverse portion lying substantially against the formation, at least a substantial number of the holes receiving limbs of more than one unit and the transverse portions defining a mesh-like arrangement anchored at least partly by the reinforcing limbs.
At least some of the units can cGmprise a U-shaped configuration providing a pair of spaced retaininy limbs and a --transverse portion connecting the limbs, the transverse portions lying adjacent to the earth formation.
.
Means may be provided for inhibiting removal of the limbs from the holes, if needed. The inhiblting means may comprise locking formations provided by the retaining limbs of the units for anchoring the limbs in the holes, and additionally or optionally may comprise grouting material anchoring the retaining limbs in the holes. The concept of using each hole 20 for multiple anchorage provides unique system characteristics.
The system becomes extremely fle~lble since the number of limbs inserted into each hole can be varied according to requirements.
Consequently, the tensile and shear strengths can be easily varied and a greater surface area can be provided for the bonding of the grout.
In one embodiment, the lengths of the retaining limbs are between 0,5 and 2 metre, and the lengths of the transverse portions are in the range of 0,5 to l metre.
A restraining unit suitable for an earth reinforcing and confining system may have a U-shaped configuration providing a pair of spaced retaining limbs for insertion into suitable spaced holes in an earth formation and a transverse portion connecting the limbs, the limbs having lengths of between 0,5 and 2 metres and including means for inhibiting removal of the 10 limbs from suitably prepared holes, and -the space in between the limbs being in the range of 0,5 and l metre.
Embodiments of the invention will now be described, by way of example, with'reference to the accompanying drawings, in which Figure l shows a restraining unit for a reinforcing and confining system;
Figure 2 is a cross-section through an earth formation illustrating part of a rock reinforcing and confining systPm;
Figure 3 shows an arrangement of part of the system of 20 Figure 2 in the direction of arrow III in Figure 2;
Figure 4 shows three different system patterns;
Figure 5 is a cross-section through a rock formation showing part of another system;
Figure 6 is a schematic representation of part of reinforc-ing and confining system; and Figures 7 to lO show reinforcing and confining uni.ts.
1 1 B2~07 Referrirlg firstly to Figure 1, a restraining unit 10 for a rock reinforcing and confining system comprises an element 12 of round iron bar. This bar has been bent so that it has a generally U-shaped configuration providing a pair of spaced retaining limbs 14 which are united by a transverse central portion 16 of the unit~
The limbs 14 extend away from opposite ends of the central portion 16 and the central portion is substantially perpendicular to the directions in which the limbs extend. As 10 shown in Figure 1, each limb is bent to form substantially sinusoidal locking kinks 18 at portions closer to the central portion 16 than to the free ends of the limbs. The limbs also have relatively straight portions 20 extending away from the locking kinks.
The element 12 may suitably have a diameter o~, for example, 9 mm and the limbs may be about 1 metre long. The central portion 16 may also be about 1 metre long, or possibly slightly less than this. Naturally, the lengths of the limbs and of the central portion will be varied depending on the 20 selected drill hole density and required drill hole depth.
In practice, rock units suitable for use with drill hole depths of 1 metre, 1,5 metre and 2 metres and drill hole spacings of 1 metre, 0,75 metres and 0,5 metres would probably suit most requirements.
.
.
~ 1 ~2~
The unit of Fiyure 1 may be used in the reinforcing and confining system of Figure 6, part of which is shown in detail in Figures 2 and 3, by drilling holes 22 into a rock formation 24 with the central axes of the holes being the same distance apart as the limbs 14 of the units 10 to be used. The diameters of the holes should be selected to allow for an appropriate number of limbs to be anchored in each hole. The depths of the holes may be selected to allow for the limbs to be anchored to substantially their full depth.
10 Once the holes have been drilled into the rock forma-ton, the limbs of the units are inserted into the holes and are O
pushed into the holes until the locking kinks 18 reach the mouths of the holes. The limbs are then driven into the holes with a suitable hammer ând the kinks will serve to anchor the limbs in place. The kinks are shown out of proportion to the hole diameter in the Figures. Where rapid installation and a minimum support life is required, the units may be driven into position without any grout, relying solely on the action of the locking kinks to retain them in position. However, the unlts 20 will normally be grouted into position by grouting material 25 to protect them from deterioration.
The limbs 14 of the various UllitS passing into each hole may be passed through a central hole 26 in a locating element in the form of a locking washer 28 before being inserted into thë hole. The locking washer adjacent to each hole may then ensure that any direct loading on a particular unit will be transmitted to the adjacent units.
: ~ 3 ~07 g Once the limbs 14 of the units have been properly located in the holes 22, the central portions 16 of the units will effectively form a mesh formation close to the contour of the face of the rock formation. By using a standard drilling pattern with a constant spacing, it is possible to alter the mesh openings to cater for a large range of rock formation sizes. This is done by simply locating larger or smaller numbers of units in each hole and by interlinking different holes. The mesh density can be further altered by changing the 10 spacing of the drill holes.
Figure 4 shows three basic patterns of units based on a square-grid system of drill holes 22. The drill holes are arranged in logitudinal rows 30 which are spaced one metre apart and transverse rows 32 which are also spaced one metre apart. In the zone 34, units are driven into the holes 22 with their central portions 16 extending only in the directions of the rows 30 and 32. A square mesh pattern is thus formed.
In the zone 36, the mesh pattern shown in the zone 34 is continued but a diagonal pattern of additional units is 20 superimposed on the square pattern to form a relatively dense mesh pattern.
Finally, in zone 38, the square mesh pattern is no longer continued but the diagonal mesh arrangement is retained, forming a diamond mesh pattern. This ls the form shown in Figure 6.
~ J 62~07 Figure 4 thus illustrates that it is possible for the units to cross the rock formation in different directions while being linked together at points which are anchored deep into the rock formation. The resulting mesh formation will oppose the deformation of the rock formation and will transmit point loads across a large area.
With reference to Figure 5, the U-shaped units may be arranged to provide two or more mesh layers 40. In this case, an increased number of locating elements, in this case also 10locking washers 28, is preferably used, the washer 28 closest to the hole surrounding the limbs of the units forming all of q the layers, a second locking washer surrounding the limbs of the units forming the outer two layers and the third locking washer surrounding only the limbs of the units of the outer mesh layer. The layers may have limbs of differing lengths anchored in a common drill hole grid or in an alternative drill hole` grid. This arrangement lS particularly suitable for inhibiting the damaging effects of violent rock bursts because each consecutive layer of mesh takes load at different time 20intervals, preventing the instantaneous release of strain energy at the rock face.
In the past, rock support systems have mainly been active support systems, such as traditional rock bolt systems, which immediately exert and maintain restraint against rock failure action after installation or passive support systemsi such as steel or timber props and packs which become effective only after rock failure has occurred. The system of the .
' 1 ~ e24.07 --ll--invention can form a comp~site reinforcing and confininy structure such as that shown in Figure 6 ~the rock formation being omitted), and thus provides a support lining for a rock formation and in situ rock reinforcement. The system has active and passive support ability, providing increased stiff-ness of the reinforced rock formation and yieldability if the rock ~ormation begins to move.
The system may be used with suitable linings for sealing rock faces and helping to maintain the integrity of 10 rock faces. While the system can be used in combination with wire mesh, shotcrete or gunnite (that is cementitious mater~al projected forcibly against the rock face), or sprayed plastics linings, the system can enhance the yieldability and strength - of all these linings aliowing them to absorb strain energy release while still supporting a rock formation, wire mesh and shotcrete being most suitable.
Although the uni.ts have been described in connection with supporting rock formations, it is possible that they could also be used elsewhere. For example, they could be used as 20 reinforcing members for concrete work, for supporting the perimeter of yieldable concrete packs or in steel rope lacing for improving stope hanging wall support.
The material and shape of the unit will be selected to suit the particular application. Possible alternative shapes are shown in Figures 7 to lO.
1 ~ ~2~.07 The unit of Figure 7 is a simple L-shaped unit formed of similar material to the unit of Figure 1 but having a loop at the free end of its transverse portion.
The limbs of other units can pass through this loop when they are driven into holes in a rock formation, thus anchoring the free end of the transverse portion.
The units of Figures 8 and 9 are bent to form one and two doubled-back transverse portions, respectively.
This arrangement thus provides U-shaped formations which 10 servè the same purpose as the loop of Figure 7. The uni.t of Figure 10 simply has a double U-shaped configuration and can be used in a similar manner to two uni.ts of Figure 1.
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Claims (21)
1. A method of reinforcing and confining an earth formation by means of a plurality of restraining units, the units each having at least one retaining limb for insertion into one of a number of pre-formed holes in the earth formation and at least one trans-verse portion for lying substantially in contact with the surface of the formation, wherein the retaining limbs are inserted into respective pre-formed holes at least a substantial number of said holes receiving limbs of more than one unit, whereby the transverse portions of said units having limbs in one said hole extend substantially in contact with the surface of the earth formation such that said units form a mesh-like arrangement anchored at least partly by said retaining limbs.
2. A method according to claim 1, in which the end regions of the transverse portions are anchored to hold the transverse portions substantially against the earth formation.
3. A method according to claim 2, wherein at least some of the units have at least two retain-ing limbs and these limbs are forced into the holes to anchor the units.
4. A method according to claim 3, wherein the retaining limbs are forced into the holes to a depth of between about 0,5 and 2 metres.
5. A method according to claim 2, which includes linking at least some of the units to other units.
6. A method according to claim 5, wherein the retaining limbs of at least some of the units are linked by locating elements when the retaining limbs are inserted into the respective holes.
7. A method according to claim 2, wherein the prepared holes in the earth formation are formed in an array with the spacings between the holes being substantially equal to the lengths of the transverse portions of selected units, and wherein a plurality of retaining limbs are inserted into the majority of said holes.
8. A method according to claim 7, wherein the spacings between the holes is in the range of 0,5 to 1 metre.
9. A method according to claim 2, wherein the retaining limbs include means for inhibiting the removal of the limbs from the holes and the inhibiting means are forced into the holes when the retaining limbs are inserted into the holes.
10. A method according to claim 9, wherein the retaining limbs are grouted into the holes.
11. A system reinforcing and confining an earth formation, the system comprising a plurality of restraining units each having at least one retaining limb inserted into one of a number of pre-formed holes in the earth formation and at least one transverse portion in contact with the surface of the formation, at least a substantial number of said holes receiving limbs of more than one unit and the transverse portions of said units having limbs in one hole extending in contact with the surface of the formation to different other holes so that said units form a mesh-like arrange-ment anchored at least partly by said retaining limbs.
12. A system according to claim 11, wherein at least some of the units comprise a U-shaped config-uration providing a pair of space-d retaining limbs and a transverse portion connecting the limbs, the trans-verse portions lying adjacent to the earth formation.
13. A system according to claim 11, including means for inhibiting removal of the limbs from the holes.
14. A system according to claim 13, wherein the inhibiting means comprises locking formations provided by the retaining limbs of the units for anchoring the limbs in the holes.
15. A system according to claim 14, wherein the inhibiting means further comprises grouting mater-ial anchoring the retaining limbs in the holes.
16. A system according to claim 14, including means linking together limbs received in respective holes.
17. A system according to claim 16, wherein the lengths of the retaining limbs are between 0,5 and 2 metres.
18. A system according to claim 17, wherein the lengths of the transverse portions are in the range of 0,5 to 1 metre.
19. A system according to claim 11, wherein the plurality of restraining units each has a U-shaped configuration providing a pair of spaced retaining limbs for insertion into suitably spaced holes in an earth formation and a transverse portion connecting the limbs, the limbs having lengths of between 0,5 and 2 metres and including means for inhibiting removal of the limbs from suitably prepared holes, and the space in between the limbs being in the range of 0,5 to 1 metre.
20. A system according to claim 19 r in which the inhibiting means are formations provided by the limbs.
21. A system according to claim 11, wherein the plurality of restraining units each has a U-shaped configuration providing a pair of spaced retaining limbs in suitably prepared holes in an earth formation and a transverse portion connecting the limbs, a sub-stantial number of said holes receiving limbs of more than one unit, the limbs having lengths of between 0,5 and 2 metres and including formations in said holes for inhibiting removal of the limbs from said holes, and the space in between the limbs being in the range of 0,5 to 1 metre; means linking together limbs received in respective holes; and grouting material further anchoring said limbs in said holes.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ZA79/6363 | 1979-11-23 | ||
| ZA796363 | 1979-11-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1162407A true CA1162407A (en) | 1984-02-21 |
Family
ID=25574378
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000365214A Expired CA1162407A (en) | 1979-11-23 | 1980-11-21 | Reinforcing and confining earth formations |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US4413928A (en) |
| CA (1) | CA1162407A (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ZA838486B (en) * | 1982-11-16 | 1984-06-27 | Tucker Michael C | A method and apparatus for reinforcing and consolidating earth structures |
| US4610568A (en) * | 1984-03-28 | 1986-09-09 | Koerner Robert M | Slope stabilization system and method |
| US4618283A (en) * | 1984-09-06 | 1986-10-21 | Hilfiker Pipe Co. | Archway construction utilizing alternating reinforcing mats and fill layers |
| US4634318A (en) * | 1984-11-23 | 1987-01-06 | George Koumal | Integrated rock reinforcement system and method using a continuous cable |
| US4610572A (en) * | 1985-08-29 | 1986-09-09 | Tekken Construction Co., Ltd. | Method of building strengthened embankment body |
| US5415498A (en) * | 1993-06-24 | 1995-05-16 | Seegmiller; Ben L. | Mine roof support systems and components |
| JP2009203681A (en) * | 2008-02-27 | 2009-09-10 | Purotekku Engineering:Kk | Rock fall preventing structure and rock fall preventing method |
| GB201417357D0 (en) * | 2014-10-01 | 2014-11-12 | Bergeron Jean Pierre | Protective Rod For Landscape |
| US10415387B2 (en) * | 2016-07-08 | 2019-09-17 | Shandong University | High-strength confined concrete support system for underground tunnel |
| CN106894833B (en) * | 2017-01-23 | 2018-04-06 | 山东科技大学 | Gob side entry driving unbalanced support structure and construction method under the unstable overlying strata in deep |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US360225A (en) * | 1887-03-29 | Embankment-protector | ||
| US589856A (en) * | 1897-09-14 | eabitz | ||
| US1358042A (en) * | 1915-05-27 | 1920-11-09 | George W Warmoth | Roadway reinforcement |
| US1559560A (en) * | 1924-02-11 | 1925-11-03 | Walter H Doughty | Roof support for mines |
| US2143461A (en) * | 1937-07-28 | 1939-01-10 | Frank M Waring | Means for preventing soil erosion |
| US2318349A (en) * | 1940-12-02 | 1943-05-04 | Bryce R Wiley | Erosion check dam |
| US3412561A (en) * | 1965-12-16 | 1968-11-26 | Reid Giorgina | Reed-trench terracing |
| FR2094557A5 (en) * | 1970-06-25 | 1972-02-04 | Rhodiaceta | Beach cleaning - by covering with nonwoven polyester fabric |
-
1980
- 1980-11-17 US US06/207,554 patent/US4413928A/en not_active Expired - Lifetime
- 1980-11-21 CA CA000365214A patent/CA1162407A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| US4413928A (en) | 1983-11-08 |
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| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |